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Date: Thu, 06 Apr 2006 17:39:39 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai-core] Frozen timer IRQ
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Jan Kiszka wrote:
> Philippe Gerum wrote:
> 
>>Jan Kiszka wrote:
>>
>>>Attached is an ipipe-freeze of the frozen system. It's taken at the time
>>>the main thread of the terminating application has successfully
>>>rt_task_join'ed the last remaining RT-thread. I took 2000 trace points
>>>before and after that point and additionally instrumented
>>>rthal_timer_program_shot() (special trace 0x01, the argument is the
>>>delay). The interesting stuff happens around 600 us after the freeze: it
>>>seems the scheduled Linux timer arrives then but doesn't get much
>>>attention beyond from ipipe.
>>>
>>>Any idea what to look for next? I have a "perfect" test system now,
>>>though I still see no light at the end of the tunnel how to export it to
>>>other boxes.
>>>
>>>Enough for today.
>>>
>>>Jan
>>>
>>>
>>>PS: This trace was taken over 2.6.15 to exclude any issues with the new
>>>2.6.16. Both kernels show the same effect.
>>>
>>
>>Does this patch make any difference?
>>
>>--- ipipe-root.c~    2006-01-31 09:55:44.000000000 +0100
>>+++ ipipe-root.c    2006-04-06 17:01:49.000000000 +0200
>>@@ -328,9 +328,8 @@
>>         /* Only sync virtual IRQs here, so that we don't recurse
>>            indefinitely in case of an external interrupt flood. */
>>
>>-        if ((ipipe_root_domain->cpudata[cpuid].
>>-             irq_pending_hi & IPIPE_IRQMASK_VIRT) != 0)
>>-            __ipipe_sync_stage(IPIPE_IRQMASK_VIRT);
>>+        if (ipipe_root_domain->cpudata[cpuid].irq_pending_hi != 0)
>>+            __ipipe_sync_stage(IPIPE_IRQMASK_ANY);
>>     }
>> #ifdef CONFIG_IPIPE_TRACE_IRQSOFF
>>     ipipe_trace_end(0x8000000D);
> 
> 
> Nope.

That's good news, actually. I would have been quite embarrased if it did it.

> 
> Where should I put my finger on to find out what's happening?
> 

It seems that the pipeline log is not synced by __ipipe_unstall_iret_root.
We need to know why. Question: is the root stage stalled or unstalled by this
routine during the latest call before the box freezes?

PS: it would be nice to display the status of the current stage
(stalled/unstalled) and the one of the hw interrupt bit, for each trace.

> Jan
> 


-- 

Philippe.